Artificial creams intended for the above purposes have traditionally been made with the inclusion of protein derived from milk either as spray-dried milk powder or sodium caseinate. Protein has a multi-purpose function in these systems:
It can be seen that the production of a multifunctional liquid cream becomes a complicated task when protein is eliminated. This is primarily due to the fact that the basic functional requirements of a liquid coffee creamer and of a whippable cream are, at least partially, mutually exclusive. On whipping, the emulsion partially destabilises to give agglomerated fat globules forming a network within the foam lamellae. However, this destabilisation must only occur during high shear, i.e. whipping, otherwise the product will be unstable in the liquid form during the distribution cycle.
The protein function has been replaced in bakery creams by methylethylcellulose. Here the degree of substitution of the cellulose molecule enables the compound to be absorbed at the interface and give a stable liquid. This, as in the case of protein, is overcome during high shear allowing fat agglomeration and therefore stable whipped cream. Unfortunately methylethylcellulose is insoluble in hot water and thus precipitates in hot coffee to give a white surface scum.
The main objective was therefore to discover a blend of emulsifiers and stabilisers which would allow for the manufacture of a stable liquid which perform all the functions previously outlined without the use of protein.
Where protein is present the functions of other emulsifiers added to whipping creams is to give a good volume to the whip, modify the foam texture and provide stability against syneresis. The standard emulsifiers used are lipophilic and include various monoglycerides, and the alpha-tending emulsifiers e.g. propylene glycol monostearate, acetylated monoglycerides and lactylated monoglycerides. These alpha-tending emulsifiers form a rigid alpha-crystalline film on the surface of the fat globules and promote fat agglomeration during whipping when the stabilising protein is disrupted by high shear.
In the absence of protein the use of the above emulsifiers is counter-productive in allowing fat coalescence in the liquid phase and therefore instability. Using the range of permitted emulsifiers various combinations have been tried in order to produce a stable liquid emulsion which is whippable to a defined peak. It has been found that a combination of Tween 60, sodium stearoyl lactylate and soya lecithin in the ratio of 3:3:1 will give a stable liquid emulsion, particularly where the apparent HLB (Hydrophile-Lypophile Balance) is 8-9. The stability of this product appears to be due to the fact that sodium stearoyl lactylate is anionic and charge repulsion at the oil droplet surface prevents agglomeration. A stabilised cream with the above emulsifier balance at a total level of 0.35% will whip a mechanical whippable machine to a light spoonable cream. The firmness/definition of the whipped product can be enhanced by the addition of cations. This is believed to be due to partial neutralisation of the negative charge of SSL at the interphase and thus allowing some oil droplet agglomeration on high shear.